DETROIT — The financial crisis is the only thing Barack Obama and John McCain talk about these days.

But neither nominee would commit Sunday to actually returning to the Senate this week to vote on the $700 billion bill aimed at preventing widespread economic collapse.

The dichotomy between their campaign trail rhetoric and their absence in the Senate is nothing new in this presidential race. Both nominees have spoken extensively in their travels over the last 20 months about bills on which they do not vote because they could not make it back to the Senate.

Yet no other piece of legislation has dominated the debate in this election cycle nearly as much as the financial bailout.

Though McCain took the unusual step last week of threatening to skip the first presidential debate to focus on the crisis, he may not make it back to Capitol Hill to weigh in on the legislation.

“It’s impossible to know until the vote has been announced,” McCain spokesman Tucker Bounds said Sunday.

The Obama campaign was equally noncommittal.

“We are closely monitoring the vote schedule,” Obama spokeswoman Jen Psaki said. “Senator Obama has always said that when the vote is close and his vote is needed he will be there.”

The Senate vote could come as early as Monday afternoon, when the candidates are scheduled to appear in states crucial to their electoral hopes—as Obama campaigns in Colorado and McCain in Ohio. If the vote is delayed until Wednesday, McCain will be in Washington D.C. for part of that day.

If they do cast votes, it would be the first for McCain since March 14, and the first for Obama since July 9, according to a database maintained by the Washington Post.

Before the negotiations collapsed last week, both candidates were initially uncertain about whether they would return for the vote.

On Monday, McCain campaign manager Rick Davis said their candidate “retains his rights to evaluate it as it goes along and make a final decision.” By Wednesday, McCain announced he would suspend his campaign and possibly skip the debate. He arrived Thursday on Capitol Hill, but hasn’t been back there since Friday morning.

Obama aides said last week that the Democrat would make the bailout vote if the tally looked close. He attended a White House meeting Thursday, but has otherwise monitored the negotiations through calls with congressional leaders and Treasury Secretary Henry Paulson.

If they do make it to the Senate, both candidates indicated Sunday that they were likely to back the bill.

“My inclination is to support it because I think Main Street is now at stake,” Obama said on CBS’s “Face the Nation.”

Obama said later Sunday at a rally here that it was an “outrage that we are now being forced to clean up their mess,” referring to Wall Street speculators and Washington regulators.

“But we have no choice,” he said. “We must act now. Because now that we’re in this situation, your jobs, your life savings, and the stability of our entire economy are at risk.”

McCain aides said during a conference call Sunday with reporters that the campaign was looking at the proposal.

“I’d like to see the details, but hopefully yes,” McCain said on ABC’s “This Week,” when asked if he would vote for the bill. “And the outlines that I have read of it, that this is something that all of us will swallow hard and go forward with. The option of doing nothing is simply not an acceptable option.”